Compressed stabilized earth blocks (CSEBs) are an earthen building material made from soil, cement, and water. CSEB can be considered as an environmentally friendly and sustainable alternative to traditional bricks and cement blocks. Since the main raw material of CSEB is soil, the clay content in the soil greatly affects its strength and durability. Hence fibre can be used to improve ductility and toughness. This study provides an experimental analysis of the properties of CSEBs reinforced with PET (Polyethylene Terephthalate) fibres. Further controlling of soil gradation was carried out by using construction waste and applying the particle packing optimization concept. Furthermore, the study highlights soil gradation was adjusted to match the optimization curve for producing CSEBs. To compare dry and wet compressive strength, water absorption, and dry density with SLS 1382:PART 1 requirement, test cubes (150mmx150mmx150mm) were cast with 20% finer content and 10% cement for different PET fibre lengths (1cm, 2cm, 3cm,4cm) and different PET fibre percentages by weight (0.1%,0.2%,0.3%,0.4%). Out of the test cubes, 0.4 weight percentage and 2cm length PET-reinforced CSEB were selected as optimum. So, with those results optimum industrial blocks(356mmx178mmx102mm), were cast and industrial scale blocks results satisfied Grade 1 SLS 1382: PART 1 requirement. This study also concerns the cost-effectiveness of the blocks.